Recent portable telephones having remarkably advanced performances and various and many functions may well deserve to be called portable computers, rather than telephones. In addition to the telephone function, a portable telephone has functions of a clock, a calculator, a game machine and Internet accessing. As such, the portable telephone also operates as a platform allowing operation of separate application programs (hereinafter simply referred to as applications) including full browser and electronic mail.
The portable telephone that is no longer a simple telephone but rather a portable information terminal still has problems to be solved. The most serious of the problems is an interface to man.
As the portable telephone comes to have higher functions as described above, there arises a demand for simultaneously activating a number of applications at one time. State of the art realizes simultaneous activation of a number of applications at one time relatively easily, even if the portable telephone is of a small size. It is noted, however, that conditions for outputting pieces of information when a plurality of applications are activated in such a manner are far severer for a portable telephone than a computer.
A portable telephone must be small to be portable for the namesake. Further, keys or buttons must be provided to allow input of information. Therefore, of the body area, not much area can be used as a monitor and, therefore, a general portable telephone has only a small monitor.
In contrast, a desktop computer allows viewing of a large amount of information at one time on a large monitor. Manners of display when a number of applications are activated at one time have also been established. A typical example is shown in FIG. 1.
Referring to FIG. 1, on a monitor screen 10 of a desktop computer, windows 12 and 4 are displayed for different applications, and display for each application is given in the corresponding window. In some cases, it is possible to display a plurality of windows for one application.
When a plurality of windows are displayed on the monitor in this manner, windows may possibly overlap. In such a case, according to the conventional technique, when a user places and clicks a mouse pointer on a point of aimed window, the window is activated and control is passed to the application corresponding to the window. When the number of windows increases, however, a window or windows may be completely hidden by other windows. For such a situation, there are some contraptions by which windows are activated in turn by pressing keys of a specific combination, or the plurality of windows are listed, allowing the user to select arbitrary one.
When a plurality of windows such as shown in FIG. 1 are displayed on a small monitor of a portable telephone, however, windows are overlapped and viewing becomes difficult, or a window is hidden by another window and selection of an arbitrary window is hindered. If a contraption to select an arbitrary window as described above is to be prepared, it becomes necessary to press keys of a specific combination or to press buttons. Considering increased frequency of such operations, such a contraption merely results in complicated operations. Therefore, it is impractical to use similar scheme as in a conventional desktop computer in a device as represented by a portable telephone having only a small monitor.
A solution to such a problem is disclosed by T. Aoyama, in Japanese Patent Laying-Open No. 2003-283635. FIG. 2 shows a manner of displaying images of a plurality of applications on a portable telephone disclosed by Aoyama. Referring to FIG. 2, on a display screen 26 of the portable telephone according to Aoyama, a plurality of tabs 20, 22 and 24 are displayed. By selecting a desired one of these tabs, a corresponding image appears on the display screen 26. By switching the tabs, it is possible to display images of a plurality of applications successively.
Such a display method, however, allows display of only one window at a time, and it is impossible to display a plurality of windows at one time. If it is necessary to simultaneously activate a plurality of applications and to operate the plurality of applications in a linked manner, the method according to Aoyama is inconvenient.
Sato et al. discloses another solution to such a problem, in Japanese Patent Laying-Open No. 2006-59117. FIG. 3 shows an example of display. Referring to FIG. 3, according to Sato et al., the portable telephone has a display screen 30, which is divided to upper and lower two areas 32 and 34. Outputs of separate applications are displayed on areas 32 and 34.
Sato et al. points out a problem that when the display screen 30 is divided to a plurality of areas and allocated to separate applications, it is difficult for the user to easily grasp which key input leads to which image of which application. Sato et al. further discloses, as a solution to such a problem, that when an application is activated, an indication to that effect is displayed on the display screen 30.
Patent Document 1: Japanese Patent Laying-Open No. 2003-283635 (FIG. 2)
Patent Document 2: Japanese Patent Laying-Open No. 2006-59117 (FIG. 3)